Mining nematode protein secretomes to explain lifestyle and host specificity.

Parasitic nematodes are highly successful pathogens, inflicting disease on humans, animals and plants. Despite great differences in their life cycles, host preference and transmission modes, these parasites share a common capacity to manipulate their host's immune system. This is at least partly achieved through the release of excretory/secretory proteins, the most well-characterized component of nematode secretomes, that are comprised of functionally diverse molecules. In this work, we analyzed published protein secretomes of parasitic nematodes to identify common patterns as well as species-specific traits. The 20 selected organisms span 4 nematode clades, including plant pathogens, animal parasites, and the free-living species Caenorhabditis elegans. Transthyretin-like proteins were the only component common to all adult secretomes; many other protein classes overlapped across multiple datasets. The glycolytic enzymes aldolase and enolase were present in all parasitic species, but missing from C. elegans. Secretomes from larval stages showed less overlap between species. Although comparison of secretome composition across species and life-cycle stages is challenged by the use of different methods and depths of sequencing among studies, our workflow enabled the identification of conserved protein families and pinpointed elements that may have evolved as to enable parasitism. This strategy, extended to more secretomes, may be exploited to prioritize therapeutic targets in the future. Author summary: Parasitic helminths (worms) cause long-lasting infections. In order to survive in their hosts, this class of pathogens has developed various strategies; one of them consists of releasing soluble mediators (e.g., excretory/secretory (ES) proteins), which dampen the host immune response. Here, we analyzed and compared published ES protein catalogs of parasitic nematodes to identify common patterns as well as species-specific traits. Many proteins were common to multiple species, and a few were absent in secretions from the non-parasitic species Caenorhabditis elegans. This was the case of two glycolytic enzymes, aldolase and enolase, for which alternative functions have been proposed by others. A role in parasitic processes is intriguing. Our workflow enabled the identification of conserved protein families and pinpointed elements that may have evolved as to enable parasitism. This may prove useful in the future to identify and prioritize potential targets for therapeutic interventions. [ABSTRACT FROM AUTHOR]